Electronegativity effect of (Z[tbnd] S, O, F and Cl) doping on the electrical, electron density and optoelectronic properties of half-Heusler LiMgP: DFT overview

Abstract

In this paper, the effect of (Z S, O, F and Cl)- dopant has been exanimated on the electronic structure and optoelectronic properties of LiMgP alloy, where the Z amount is 6.25%. Hence, the considered systems are Li16Mg16P15S, Li16Mg16P15O, Li16Mg16P15F and Li16Mg16P15Cl. The LiMgP alloy has an XYZ arrangement which is crystallized in the (N° 216) space group. The present investigation is carried out within the Wien2K package combined with the TB-mBJ approach. Within the study, the Burstein–Moss shift is observed when (Z S, O, F and Cl) where the n-type occurred and the Fermi level lies inside the conduction band (CB). This conduct is significant because it allows obtaining various optical characteristics for the same material. The calculated apparent band gap follows the trend: (Eg+ΔE)Li16Mg16P15Cl>(Eg+ΔE)Li16Mg16P15F and (Eg+ΔE)Li16Mg16P15S>(Eg+ΔE)Li16Mg16P15O. This suggests that the halogen family (Cl and F) has much more effect on LiMgP than the chalcogen family (O and S). Based on the dielectric function, doping leads to a strong move of the absorption edge to low energies, in which four sharp peaks appear at 0.3, 0.6, 0.9 and 1.1 eV due to S, O, Cl and F elements, respectively.